Self-propelled slip form paving machines for forming continuous curbs and gutters, sidewalks, safety barriers or the like by causing concrete or other suitable flowable material to be molded by a slip form mounted on the machine are well known. These paving machines typically comprise a frame, a drive engine, a hopper for concrete or other suitably flowable paving material and a mold in the desired configuration of the pavement to be formed i.e. sidewalk, curb, gutter, safety barriers etc. Typical machines are manufactured by Gomaco Corporation Inc., Power Curbers Inc. and others. See for example U.S. Pat. No. 5,662,431; U.S. Pat. No. 6,508,606. Manually operable concrete curb and gutter apparatus are also known. For example, see U.S. Pat. No. 4,566,823 and U.S. Pat. No. 5,527,129.
While these known devices adequately form a curb of standard height, problems are encountered when the height of the curb needs to be lowered to accommodate driveway entrances or ramps. If no provision is made for forming a section of the curb with a lowered height (dropped curb), the curb would need to be cut with a concrete saw after the concrete is cured. This is time consuming and does not provide a finished appearance to the concrete surface.
To overcome this problem several different solutions have been proposed. The most common approach is the use of a vertical plate that can be placed in the slip form in order to reduce the height of the curb by reducing the height of the concrete being extruded through the form. When the vertical plate (knife) is lowered to form a dropped curb for a driveway entrance the concrete is ripped off leaving a rough surface. In order to finish the surface, it is necessary to have up to four men following the slip form concrete mold and gutter device to form up and hand trowel the dropped concrete surface to remove excess concrete and finish the surface. This is time consuming and physically demanding work as the laborers are bent over continuously. This slows down the number of linear feet of curb that can be formed in a day and adds to the expense of the project. Examples of these types of devices are illustrated in U.S. Pat. No. 3,797,958 and Canadian Patent No. 2,043,773 and are found on machines such as the GT-6300 Curb & Gutter paver from Gomaco.
Other proposed solutions involve replacement of the mold, as shown for example in U.S. Pat. No. 5,662,431. U.S. Pat. No. 6,709,195 utilizes a moveable tailpiece that is rotated into position at the end of the mold to form a low curb section. None of these proposed solutions have proven to be effective and simple to operate.
There is a need for a device that will finish the surface of the dropped curb concrete, reduce the manpower required and improve the number of lineal feet that can be formed in a day where a number of driveway entrances or ramps need to be formed.